Water bear DNA unlocks secrets of survival in extreme conditions

BY
JAMES SMITH
| PUBLISHED:
08-01-2017

The scientists found that tardigrades and nematodes were missing the same five HOX genes, which are responsible for setting the nose-to-tail pattern in embryos .

An international team of researchers has pieced together the DNA for two species of tardigrades also known as water bears to reveal the genes responsible for their amazing ability to survive in the most extreme conditions.

The study by researchers led by Mark Baxter at the University of Edinburgh and Kazuharu Arakawa at the University of Keio, Japan, is published in the open access journal PLOS Biology.

The microscopic water bear is known for its ability to resurrect itself after years of total desiccation. Once dehydrated, the hardy critter can withstand being frozen in ice, exposure to radiation, and sojourns into space.

Recently, scientists suggested that the tardigrade's DNA was a weird mixture of animal and bacterial components. But the new study, which finds that water bear DNA appears normal, shoots down that idea.

By analyzing the DNA, the researchers obtained new clues about where tardigrades sit on the tree of life. Because of their eight tiny legs, the accepted view has been that tardigrades are more closely related to arthropods spiders and their kin than to their other close cousin, the nematode.

Surprisingly, the DNA analysis indicated that water bears are more closely related to nematodes.

The scientists found that tardigrades and nematodes were missing the same five HOX genes, which are responsible for setting the nose-to-tail pattern in embryos .

The researchers also pinpointed the genes water bears use to protect themselves from complete dehydration. They identified a set of proteins that seem to replace the water lost by cells and help preserve the cellular structure until water is again available.

"I have been fascinated by these tiny, endearing animals for two decades," said Prof. Baxter, in a statement, adding, "This is just the start with the DNA blueprint we can now find out how tardigrades resist extreme, and perhaps use their special proteins in biotechnology and medical applications.